On April 23, 1967, after a more than a two-year gap in human space flight, the Soviet Union announced the launch of a new-generation spacecraft called Soyuz-1 ("union") with veteran cosmonaut Vladimir Komarov onboard. Customary for the secretive Soviet space program, the official report contained generalized statements about testing of a new spaceship but no details on its design or its mission. However, the next day, the USSR followed up with the announcement that Komarov had tragically died on landing due to a failure of the parachute system.

Unmanned launches of the Soyuz spacecraft, which preceded Komarov's flight, exposed numerous flaws. Cautious engineering thinking dictated another "clean" unmanned launch, before Soyuz could be certified to carry people. However, the Soyuz developers were under pressure from their political bosses to have a "space spectacular" as soon as possible.

From the outset, the primary goal of the Soyuz 7K-OK project was the rehearsal of rendezvous in space in support of the L1 and L3 lunar exploration programs. To meet this goal, early missions of the Soyuz spacecraft always included a dual flight.

By early September 1965, preparations for the first Soyuz mission began, just a month after Sergei Korolev had signed the final technical specifications for the Soyuz 7K-OK spacecraft. By that time, Korolev had already received a letter from the Head of Cosmonaut Training Center Nikolai Kamanin with a list of candidates for the first joint mission.

The 7K-OK No. 4 spacecraft lifted off from Tyuratam's Site 1 on April 23, 1967, at 03:35 Moscow Time, exactly as scheduled. Upon reaching orbit, it was publicly announced as Soyuz-1. Observers noticed that unlike Vostok and Voskhod, the very first spacecraft in the series had been given a number -- another hint that a second launch was imminent.

Despite numerous challenges, Vladimir Komarov with the help of engineers on the ground, was able to overcome all the technical problems in orbit and successfully piloted his spacecraft on a path back to Earth in the early hours of April 24, 1967.

The landing of the Soyuz-1 spacecraft on April 24, 1967, appeared to be normal until search and rescue teams reached the touchdown site. To their horror, they found the capsule crashed and engulfed in flames. It was immediately clear that the cosmonaut had never had a chance.

The investigation into the Soyuz-1 accident established that the crash of the descent module resulted from a parachute failure. However the exact culprit in the parachute malfunction has remained under question for decades.